A FLEXIBLE, AFFORDABLE, POWERFUL DIGITAL TRANSCEIVER FOR THE RASPBERRY PIJONATHAN BRANDENBURG, KF5IDY ARRL AND TAPR DIGITAL

COMMUNICATIONS CONFERENCE, 2018

WHAT DO THE FOLLOWING HAVE IN COMMON?

AMSATLibre Space FoundationUniversity of LouisianaPortland State University

ARRL AND TAPR DIGITAL COMMUNICATIONS CONFERENCE, 2018 2

ALL ARE USING THE AX5043 DIGITAL TRANSCEIVER IC

AMSAT

Golf-TEE IHU, Golf-1 IHU, Satellite Simulator

Libre Space Foundation

PocketQube Format Satellite Modules

University of Louisiana

Satellite Beacon, Education Platform

Portland State University

OreSat IHU TransceiverARRL AND TAPR DIGITAL COMMUNICATIONS CONFERENCE, 2018 3

WHAT IS THE ON SEMICONDUCTOR AX5043? A single chip, low-power digital

transceiver

Modulation and demodulation is performed on chip.

For transmit, the host processor sends the data byte stream. The AX5043 adds optional FEC and modulates for transmission

For reception, the AX5043 demodulates the signal, validates optional FEC then sends the resulting data to the host processor.

What modulation standards?

FM

GMSK

ASK

GFSK

PSK

MSK

FSK

4-FSK

AFSKARRL AND TAPR DIGITAL COMMUNICATIONS CONFERENCE, 2018 4

WHAT IS THE AX5043?

What frequencies?

From 27 MHz to 1050 MHz

What about output power?

16 dBm (40 mW)

Of course, may add an external power amplifier

What about sensitivity?

Example: -138 dBm @ 0.1 kbps, 868 MHz, FSK

Example: -108 dBm @ 125 kbps, 868 MHz, PSK

What about chip power requirements?

6.5 mA – 9.5 mA when receiving

7.5 mA when transmitting at 0 dBm

48 mA when transmitting at 16 dBm

500 nA power-down mode with clock

50 nA deep sleep current

ARRL AND TAPR DIGITAL COMMUNICATIONS CONFERENCE, 2018 5

I WANT TO PLAY!!!

I do what any of you might do… I create a custom board… for the Raspberry Pi

Why the Raspberry Pi? It’s an affordable

experimentation platform

It has the peripherals (SPI) to communicate with the AX5043

ARRL AND TAPR DIGITAL COMMUNICATIONS CONFERENCE, 2018 6

KICAD FOR THE SCHEMATIC AND LAYOUT

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OSHPARK FOR BOARDS

HAND ASSEMBLED

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DOES IT WORK?

Yes!!!

Developed several sample applications A chat application at GFSK,

435.3 MHz, 4800 symbols/sec, HDLC encoding, CRC-16

APRS frames, AFSK, 435.3 MHz, X.25 frames (I know FSK would typically be

used at 435.3 MHz. Will talk about the matching network in a moment)

Key Learning Opportunities: The documentation is a

“reference” not a “guide”.

AX-RadioLab application generates register values and sample code. These register values are

sometimes completely unexplained.

Generated code specific to On Semiconductor AX8052F100, including use of interrupts.

ARRL AND TAPR DIGITAL COMMUNICATIONS CONFERENCE, 2018 10

WHAT ABOUT HAM FREQUENCIES?

What about Ham frequencies?

AX 5043 data sheet has reference design to match the IC to a 50 Ohm antenna 169 MHz

433 MHz

470 MHz

868 / 915 MHz

ARRL AND TAPR DIGITAL COMMUNICATIONS CONFERENCE, 2018

QUITE UNIVERSAL CIRCUIT SIMULATOR (QUCS)

MATCHING NETWORK

The most interesting part of the schematic is the matching network I populated my boards for 433 MHz

Simply populate with different components for other bands

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WHAT NEXT?

Adding a power amplifier

AMSAT Golf-TEE IHU using NXP Semiconductor MMZ09312BT1 400 – 1000 MHz

~31.7 dB power gain (@ 900 MHz)

Planning an onboard GPS for beaconing

Planning a transverter for higher frequencies

ARRL AND TAPR DIGITAL COMMUNICATIONS CONFERENCE, 2018 14

DO YOU WANT ONE?

Questions / Answers

ARRL AND TAPR DIGITAL COMMUNICATIONS CONFERENCE, 2018

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CREDITS

Zach Metzinger (N0ZGO), Jesse Marroquin (K5JXM), Bill Reed (NX5R), and Jordan Trewitt (KF5COQ) Design of the Hercules LaunchPad BoosterPack featuring the AX5043

AMSAT Supporting this platform as the basis for the Golf-TEE IHU

ARRL AND TAPR DIGITAL COMMUNICATIONS CONFERENCE, 2018 16